1. Field of the Invention
This invention relates to a pneumatic nebulizing interface designed to convert an analyte-containing fluid stream into an aerosol without causing undesirable, excessive broadening and/or mixing of analyte bands. The interface can be used to supply a sample aerosol to any downstream apparatus including any detection apparatus, reaction apparatus, deposition apparatus, collection apparatus or any combination of these apparatus.
More particularly, the present invention relates to a pneumatic nebulizing interface designed to convert an analyte-containing fluid stream into an aerosol for subsequent reaction, deposition, collection or detection. In the interface, an aerosol is formed from the analyte-containing fluid stream, a sheath fluid and a nebulizing gas. The interface insures that the combined flow rate of the analyte-containing fluid stream and the sheath fluid always substantially exactly matches the self-aspiration rate of the pneumatic nebulizer. The interface maintains the matched combined flow rate without substantially altering the original feed rate of the analyte-containing fluid stream, by automatically self-adjusting the feed rate of the sheath fluid. Thus, neither suction nor back pressure act on the analyte-containing fluid stream and additional broadening and/or mixing of analyte bands in the fluid stream is avoided or minimized during the nebulization process. The present invention also relates to methods for making and using the pneumatic nebulization interface. Furthermore, the present invention also relates to analytical systems which include a fluid phase analyte separation sub-system or analyte delivery sub-system, the interface subsystem and a detection subsystem.
2. Description of Related Art
The currently known pneumatic nebulizer systems suffer from certain disadvantages that hinder their use in high-performance, fluid phase separation systems. The Venturi effect, which forms the basis of operation of pneumatic nebulizers, exerts suction upon the nebulized analyte-containing fluid stream and causes additional dispersion and/or mixing of the analyte bands in the fluid stream Thus, there is a need in the art for a pneumatic nebulizer interface to be used with fluid phase separation techniques or fluid phase analyte delivery techniques to convert an analyte-containing fluid stream into an aerosol such that the interface does not substantially adversely affect the width of the analyte bands in the fluid stream and is capable of substantially self-adjusting the combined flow rate of the analyte-containing fluid stream and a sheath flow stream to the natural self-aspiration rate of the nebulizer without substantially changing the original flow rate of the analyte-containing fluid stream.
This invention provides an interface to convert an analyte-containing fluid stream into an aerosol. The interface includes an analyte-containing fluid stream inlet, a sheath fluid inlet, a sheath fluid overflow outlet, a gas inlet, a nebulizing nozzle and an aerosol outlet. The analyte-containing fluid stream and the sheath fluid are supplied such that their combined flow rate through the nebulizing nozzle self-adjustingly substantially matches the natural self-aspiration rate of the nebulizing nozzle and does not cause substantial flow rate change and accompanying band width increase in the analyte-containing fluid stream.
The present invention provides a self-adjusting nebulizer apparatus including a first fluid inlet having a first flow resistance and supporting a first fluid flow, a second fluid inlet having a second flow resistance and supporting a second fluid flow, a nebulizing gas inlet supporting a gas flow; and an orifice, where the first fluid inlet, the second fluid inlet and the gas inlet terminate at or near the orifice, the second flow resistance is substantially negligible with respect to the first flow resistance and the first flow and the second flow combine to form a combined fluid flow having a rate that substantially matches the self-aspiration rate of the apparatus without producing substantial back pressure or suction which results in additional laminar flow-induced band dispersion or broadening in the first fluid inlet and the combined flow and gas flow combine to form an aerosol.
The present invention provides a self-adjusting nebulizer apparatus including a sample inlet having a first flow resistance and supporting a sample flow where the sample flow includes an analyte, a sheath fluid inlet having a second flow resistance and supporting a sheath fluid flow, a nebulizing gas inlet supporting a gas flow and an orifice through which the sample flow, the sheath flow and the gas flow exit to form an aerosol, where the sample inlet, the sheath fluid inlet and the gas inlet terminate at or near the orifice, the second flow resistance is substantially negligible with respect to the first flow resistance and the first flow and the second flow combine to form a combined fluid flow having a rate that substantially matches the self-aspiration rate of the apparatus without producing substantial back pressure or suction which results in additional laminar flow-induced band dispersion or broadening in the first fluid inlet.
The present invention provides a self-adjusting nebulizer apparatus including a first fluid inlet having a first resistance to fluid flow and supporting a first fluid flow, a second fluid inlet having a second resistance to fluid flow and supporting a second fluid flow, a nebulizer nozzle downstream of the first inlet and second fluid inlet, a gap connecting the first fluid inlet, the second fluid inlet and the nebulizer nozzle, and a gas inlet tube having an orifice at its distal end, where (1) the second resistance is substantially negligible with respect to the first resistance, (2) the first flow and the second flow combine in the gap to form a combined fluid flow having a rate that substantially matches the self-aspiration rate of the apparatus without producing substantial back pressure or suction which results in additional laminar flow-induced band dispersion or broadening in the first fluid inlet, and (3) the gas and combined fluid flow form an aerosol upon exiting the orifice.
The present invention provides a self-adjusting nebulizer apparatus including a first member including a distal end and having a first resistance to fluid flow and supporting a first fluid flow, a nebulizer nozzle including a proximal end and a distal end, a gap separating the distal end of the first member from the proximal end of the nozzle, a second member having a second resistance to fluid flow and supports a second fluid flow and including an inlet and an outlet associated with the gap, and a third member supporting a gas flow and including an orifice at its distal end, where (1) the distal end of the nozzle is located at or near the orifice, (2) the second resistance is substantially negligible with respect to the first resistance, and (3) the first flow and the second flow combine in the gap to form a combined fluid flow having a rate that substantially matches the self-aspiration rate of the apparatus without producing substantial back pressure or suction on the first member.
This invention also provides an analytical separation and detection system which includes a fluid phase separation subsystem or analyte delivery subsystem, a downstream deposition or detection subsystem and an interface which connects the upstream subsystems to the downstream subsystems.
This invention further provides a apparatus for generating aerosols and includes an analyte-containing fluid stream feed tube or first inner tube and a nebulizer nozzle or second inner tube separated by a liquid gap. The feed tubes or inner tubes and the gap are contained within a first outer tube having an opening at or near the gap through which a sheath fluid can enter the gap. This sub-assembly is contained within a sheath fluid delivery tube which in turn is contained within a gas delivery tube. The analyte-containing fluid stream feed tube has a diameter less than or equal to the diameter of the nebulizing nozzle. The analyte-containing fluid stream feed tube is designed to interface with or be part of a fluid phase separation subsystem or analyte deliver subsystem at its distal end. The nebulizing nozzle is designed to supply the combined flow of the analyte-containing fluid stream and the sheath fluid to an orifice where the combined flow contacts a gas and is converted into an aerosol.
This invention provides an analytical method which includes separating a sample into its components in a fluid phase. The separated analytes in the fluid phase are then forwarded to a pneumatic nebulizer interface designed to automatically adjust the flow rate of the combined analyte-containing fluid stream and the sheath liquid to substantially match the self-aspiration rate of the nebulizing nozzle without substantially altering the flow rate of the analyte-containing fluid stream. The pneumatic nebulizer interface converts the combined flow into an aerosol by contacting it with the nebulizing gas. The aerosol is then forwarded to a detection system where the analytes are detected and quantified. Moreover, the detection system may involve one or more conversion steps before detection and quantification.
This invention provides an interfacing method which includes the step of supplying the analytes in a fluid stream from a fluid phase separation apparatus or analyte delivery apparatus. Next, the analyte-containing fluid stream is introduced into an interface through an analyte-containing fluid stream feed tube. After introduction, a sheath fluid is supplied to the analyte-containing fluid stream through an opening such that substantially no adverse additional band broadening is caused in the analyte-containing fluid stream. The sheath fluid and the analyte-containing fluid streams then are combined in a gap which is located between the analyte-containing fluid stream feed tube and a nebulizing nozzle. The combined flow then exits the nebulizing nozzle in the orifice where the combined fluid flow contacts a gas to form an aerosol.
This invention provides an interfacing method which includes the step of introducing a fluid stream into an interface through a fluid stream feed tube. After introduction, a sheath fluid is supplied to the fluid stream through an opening such that substantially no adverse mixing occurs in the fluid stream. The sheath fluid and the fluid stream then are combined in a gap which is located between the fluid stream feed tube and a nebulizing nozzle. The combined flow then exits the nebulizing nozzle in the orifice where the combined fluid flow contacts a gas to form an aerosol.